There are numerous threads on how to for PCC
Would suggest you browse through them. Basically, you just apply to the local consulate (assuming you are currently residing in US).
Regarding your P3, not sure why you want to wait till after marriage, but anyways, you don\'t have to wait to apply for your PCC. I think it is valid for 6 months. If wife is coming back with you, then I would suggest to wait and request PCC together from the local consulate. If she is staying back, she will have to get it from RPO/Police in India.